In the science of blood collection for therapeutic purposes, blood is presently collected by inserting a donor needle into the vein of a donor. The donor needle communicates with a flexible, collapsible blood collection container through flexible tubing, which is connected at respective ends to the needle and the container.
The commercially available blood containers utilize a relatively long, flexible tubing connecting between the collapsible blood container and the donor needle, so that a series of segments may be formed by transverse sealing into the tubing after collection of blood plus filling of the donor tubing, so that the transverse, sealed segments in the donor tubing may be separately cut away for individual blood typing, cross-matching, and disease detecting procedures.
However, recently, because of the increase in number of potential diseases and the like for which donated blood is desirably tested, the users of blood containers, after the removing of the donor needle from the patient, are obtaining larger volumes of blood for sampling, typically by then sequentially inserting the donor needle into several evacuated vials to draw blood back out of the donor tubing into the vials. As this takes place, blood from the collapsible blood container is drawn back into the donor tubing.
Concern has arisen that the blood which has originally passed into the collapsible blood storage container is not suitable for certain forms of analytical testing of blood samples, because of the "dilution" effect provided by the liquid anticoagulant/nutrient which is initially present in the blood container into which the donated blood flows. Such anticoagulants such as CPD or ACD are believed to interfere with the accuracy of certain tests in some circumstances, for example, testing for antiHBc and for HTLV III.
Thus, there is a need for an increased supply of donated blood which has not been mixed with a liquid anticoagulant/nutrient normally found in blood storage containers, this supply being more than the volume which is typically carried in the volume of a length of donor tubing. At the same time, it is desirable for the blood collection container to optionally be capable of not collecting a significantly increased supply of blood over that normally found in the donor tubing, in those circumstances where augmented testing is not required, but only conventional testing as has been typically done in years past. In that circumstance, it of course would be desirable that an extra 20-30 ml. or so of unnecessary, collected blood should not be lost to the patient. Such unnecessary, collected blood also would present a disposal problem.
By this invention, a method is provided in which blood may be collected, with an increased volume portion of the blood collected being intended for sampling and testing, and being kept free of dilution with an anticoagulant/nutrient that is provided to stored blood. The method of this invention is compatible with a blood system in which an extra volume of such blood for sampling and testing does not have to be collected, but can be left with the patient.